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CI 77491

Last update on Feb 5, 2026

CI 77491 that is added to cosmetics is synthetic red iron oxide pigment (natural red iron oxide being rust). The chemical formula of CI 77491 is Fe2O3. This ingredient is responsible for imparting reddish or pinkish tone to cosmetic and skin care products. The main usage of iron oxide CI 77491 is to improve the way a product looks and make it more appealing to the eyes. This ingredient works well with almost all the other ingredients and is a durable and an inexpensive pigment.

CAS Number: 1309-37-1 / 1345-27-3Chem/IUPAC Name: Diiron trioxide; Ferric oxide EINECS/ELINCS No: 215-168-2 / 215-722-3COSING REF No: 32829

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What is CI 77491 used for?

Red iron oxide pigment (or CI 77491) is commonly used as a colorant in cosmetic and skin care products. This ingredient is responsible for imparting a rusty look to formulations.

  • Cosmetic products: Apart from acting as a colorant, it has a reflective property in makeup that take attention away from imperfections. This ingredient also helps even out the skin tone
  • Skin care: It provides protection against certain wavelengths of light - such as UV light, visible light, and blue light. This is why this ingredient is most commonly used in sunscreens and is more beneficial than normal sunscreens

Origin

CI 77491 is found naturally on the earth’s surface. It can be obtained by the mineral hematite. However, naturally occurring red iron oxide contains impurities such as manganese that are harmful to the skin. Therefore, synthetically made iron oxide red is generally used in cosmetic and skin care products - that is considered safer. This can be prepared by the calcination of copperas or hydrates of iron.

What does CI 77491 do in a formulation?

COSMETIC COLORANT

Safety Profile

CI 77491 is considered safe for use in skin care and cosmetic products because it is non-allergenic and non-toxic. However, a patch test is recommended prior to full application. Red iron oxide is also halal.

CI 77491 alternatives

CI 77491 technical profile

PropertyValues
Boiling Point3414°C
Melting Point1565°C
pH6.0-7.0
SolubilityInsoluble in water